import java.io.IOException;
import java.math.BigInteger;

public class Main{

	/**
	 * @param args
	 * @throws IOException
	 */
	public static void main(String[] args) throws IOException {
		java.io.BufferedReader r = new java.io.BufferedReader(
				new java.io.InputStreamReader(System.in));

		BigInteger two = new BigInteger("2");
		while (true) {
			if (!r.ready()) {
				break;
			}
			String s = r.readLine().trim();
			if (s.equalsIgnoreCase("1")) {
				System.out.println(1);
			} else {
				BigInteger n = new BigInteger(s).subtract(BigInteger.ONE);
				System.out.println(n.multiply(two));
			}
		}
	}

}
